1. Field of the Invention
The present invention relates to a display device for displaying characters, numbers, patterns, etc. The present invention also relates to electronic watches, such as a wristwatch, a stopwatch, etc., incorporating the display device. Particularly, the present invention relates to a display device, such as a liquid-crystal display element, which displays information by selecting between a state which varies the polarization axis of a linearly polarized light component transmitted therethrough and a state which does not vary the polarization axis.
2. Description of Related Art
Electronic watches are the most common display devices which make use of outdoor external light to present a display. In one of the known electronic watches, a first polarizer, a polarization axis varying optical element (polarization axis varying means), such as a liquid-crystal display element, which selects between a state for varying the polarization axis of a linearly polarized light component transmitted therethrough and a state for not varying the polarization axis of the linearly polarized light component, a second polarizer, and a reflector, are laminated in that order. The liquid-crystal display element employs TN (Twisted Nematic) liquid crystal, STN (Super-Twisted Nematic) liquid crystal, or ECB (Electrically Controlled Birefringence) liquid crystal, for example.
In the electronic watch (the display device) thus constructed, each of the first and second polarizers transmits a linearly polarized light component, of an incident light ray, in alignment with its polarization axis, while absorbing a linearly polarized light component aligned in its absorption axis perpendicular to the polarization axis. Therefore, when an external light ray enters the first polarizer, only a linearly polarized light component having the polarization axis in a first direction is incident on the polarization axis varying optical element. Out of a linearly polarized light component transmitted through an area of the polarization axis varying optical element which varies the polarization axis and a linearly polarized light component transmitted through an area of the polarization axis varying optical system which does not vary the polarization axis, one of the linearly polarized light components is absorbed by the second polarizer while the other of the linearly polarized light components is transmitted through the second polarizer and reaches the reflector. Only a light ray reflected from the reflector, namely, a light ray which is transmitted through one of the area of the polarization axis varying optical element which varies the polarization axis and the area of the polarization axis varying optical element which does not vary the polarization axis, is transmitted through the polarization axis varying optical element and the first polarizer, and based on this light ray, time is visibly recognized.
In the conventional electronic watch, out of the linearly polarized light component transmitted through the area of the polarization axis varying optical element which varies the polarization axis and the linearly polarized light component transmitted through the area of the polarization axis varying optical element which does not vary the polarization axis, only one of the linearly polarized light components is reflected from the reflector, and is then transmitted through the polarization axis varying optical element and the polarizer, and then contributes to the displaying. On the other hand, the light ray transmitted through the other area is absorbed through the second polarizer, and contributes nothing to the displaying.
The conventional electronic watch thus suffers a problem that a segment portion or a background portion becomes a dark display. The legibility and brightness of the display are greatly affected by the light quantity of linearly polarized light component transmitted through the polarizers. For the same reason in the conventional electronic watch, it is difficult to present both the segment portion and the background portion in a mirror-like image, a matte image or a color display.
Also in the conventional electronic watch, a linearly polarized light component, which is supposed to be transmitted through the polarizers, is absorbed by the polarizer and contributes nothing to the displaying, because the orientation of the polarization axis is deflected from the polarization axis of the polarizer.
The present invention has been developed in view of the above problems, and two principal objects are set as follows. A first object of the present invention is to provide a display device and an electronic watch employing the display device, which presents a high legibility and gives a reflective display made up of combinations of a diversity of textures and tones, by making use of external light and by outputting toward the user a linearly polarized light component, regardless of whether it is transmitted through the area for varying the polarization axis or the area for not varying the polarization axis.
A second object of the present invention is to provide a display device and an electronic watch employing the display device, which increases the quantity of light contributing to displaying and presents a bright display by transmitting a linearly polarized light component, even with its polarization axis deflected, through the polarizing splitter means, of linearly polarized light components, transmitted through polarizing splitter means and in order to contribute to displaying.
The present invention has been developed in view of the above background, and to achieve the first object, the following display device is provided. The display device includes first polarizing splitter means (first polarization separator) which transmits a linearly polarized light component, of an incident light ray, aligned in a first direction, while not transmitting a linearly polarized light component aligned perpendicular thereto, polarization axis varying means (polarization changing element) which selects one of a first state which varies the polarization axis of an incident linearly polarized light component when the incident linearly polarized light component is transmitted therethrough and a second state which does not vary the polarization axis when the incident linearly polarized light component is transmitted therethrough, second polarizing splitter means (second polarization separator) which transmits a linearly polarized light component, of an incident light ray, aligned in a second direction, while specularly reflecting a linearly polarized light component aligned in a third direction perpendicular to the second direction, and specular reflective means (reflecting element) which specularly reflects a linearly polarized light component, transmitted through the second polarizing splitter means, toward the second polarizing splitter means, wherein the first polarizing splitter means, the polarization axis varying means, the second polarizing splitter means, and specular reflective means are arranged in that order, and wherein the display device displays predetermined information using a first returning light ray which is specularly reflected from the specular reflective means, and transmitted through the second polarizing splitter means, the polarization axis varying means, and the first polarizing splitter means, and a second light ray which is specularly reflected from the second polarizing splitter means, and transmitted through the polarization axis varying means and the first polarizing splitter means, out of light rays which come in on the first polarizing splitter means from the side of the first polarizing splitter means diametrically opposite to the polarization axis varying means.
The specular reflective means may be a total reflection optical element for reflecting the total of or most of the linearly polarized light component incident thereon.
The total reflection optical element may be a total reflection mirror for reflecting the total of or most of the linearly polarized light component incident thereon.
The total reflection optical element may be third polarizing splitter means (third polarization separator) for reflecting the total of or most of the linearly polarized light component aligned in the second direction while not reflecting the linearly polarized light component aligned perpendicular thereto.
The specular reflective means may be a partially reflective optical element for specularly reflecting part of an incident linearly polarized light component while transmitting the remaining incident linearly polarized light component.
The partially reflective optical element may be a half mirror, in which a metal thin film is formed on the surface of a light transmissive substrate.
The partially reflective optical element may be third polarizing splitter means which transmits a linearly polarized light component aligned in a fourth direction while specularly reflecting a linearly polarized light component aligned in a fifth direction perpendicular to the fourth direction, and, because of a deflection between the fourth direction and the second direction, the third polarizing splitter means specularly reflects part of a linearly polarized light component incident thereon, while transmitting part of the incident linearly polarized light component.
The display device may include a light source for backlighting, disposed diametrically opposite to the second polarizing splitter means with respect to the intervening specular reflective means, for emitting light toward the specular reflective means, wherein the display device displays predetermined information using a linearly polarized light component which is emitted from the backlighting light source, and transmitted through the specular reflective means, the second polarizing splitter means, the polarization axis varying means, and the first polarizing splitter means.
The display device may include fourth polarizing splitter means (fourth polarization separator) which is arranged between the first polarizing splitter means and the polarization axis varying means, and transmits a linearly polarized light component aligned in a sixth direction while reflecting a linearly polarized light component aligned in a seventh direction perpendicular to the sixth direction, wherein the sixth direction is in the same direction as the first direction or is slightly deflected from the first direction.
The display device may include first light diffusing means (diffusing element), disposed between the specular reflective means and the second polarizing splitter means, for transmitting an incident light ray while diffusing the incident light ray.
The display device may include second light diffusing means, disposed between the second polarizing splitter means and the polarization axis varying means, for transmitting an incident light ray while diffusing the incident light ray in a pattern different from a pattern imparted by the first light diffusing means.
The light diffusing means may diffuse the light ray through fine surface roughness.
The display device may further include first coloration means (first coloring element), disposed between the specular reflective means and the second polarizing splitter means, for coloring an incident light ray to output a colored light ray.
The display device may further include second coloration means (second coloring element), disposed between the first polarizing splitter means and the second polarizing splitter means, for coloring an incident light ray to output a colored light ray.
The display device may further include first coloration means, disposed between the specular reflective means and the second polarizing splitter means, for coloring an incident light ray to output a colored light ray, and second coloration means, disposed between the first polarizing splitter means and the second polarizing splitter means, for coloring an incident light ray to output a colored light ray with a hue different from a hue imparted by the first coloration means.
The coloration means may be a color filter.
The coloration means may be a coloration layer attached on at least one of the plurality of polarizing splitter means.
The polarization axis varying means may include a liquid-crystal display element.
The display device may be incorporated in an electronic watch. The electronic watch may include the display device, wherein the electronic watch displays time and time measurement results in areas of the polarization axis varying means which are selected to be in a transmissive state that transmits the linearly polarized light component, transmitted through the first polarizing splitter means, therethrough with the polarization axis of the linearly polarized light component varied or in a transmissive state that transmits the linearly polarized light component therethrough with the polarization axis not varied.
The electronic watch may display time and time measurement results in a digital display in areas of the polarization axis varying means which are selected to be in a transmissive state that transmits the linearly polarized light component, transmitted through the first polarizing splitter means, therethrough with the polarization axis of the linearly polarized light component varied or in a transmissive state that transmits the linearly polarized light component therethrough with the polarization axis not varied.
The electronic watch may display time and time measurement results, in an analog display pattern corresponding to a watch hand, in areas of the polarization axis varying means which are selected to be in a transmissive state that transmits the linearly polarized light component, transmitted through the first polarizing splitter means, therethrough with the polarization axis of the linearly polarized light component varied or in a transmissive state that transmits the linearly polarized light component therethrough with the polarization axis not varied.
To achieve the second object, the present invention provides the following display devices.
A display device of the present invention may include first polarizing splitter means which transmits a linearly polarized light component, of an incident light ray, aligned in a first direction, while not transmitting a linearly polarized light component aligned perpendicular thereto, polarization axis varying means which selects one of a first state which varies the polarization axis of an incident linearly polarized light component when the incident linearly polarized light component is transmitted therethrough and a second state which does not vary the polarization axis when the incident linearly polarized light component is transmitted therethrough, second polarizing splitter means which transmits a linearly polarized light component, of an incident light ray, aligned in a second direction, reflective means which reflects the linearly polarized light component, transmitted through the second polarizing splitter means, toward the second polarizing splitter means, wherein the first polarizing splitter means, the polarization axis varying means, the second polarizing splitter means, and the reflective means are arranged in that order, and wherein the display device displays predetermined information using a returning light ray which is reflected from the reflective means, and transmitted through the second polarizing splitter means, the polarization axis varying means, and the first polarizing splitter means, out of light rays which come in on the first polarizing splitter means from the side of the first polarizing splitter means diametrically opposite to the polarization axis varying means. The display device further includes fourth polarizing splitter means which is disposed between the first polarizing splitter means and the polarization axis varying means, and transmits a linearly polarized light component, of an incident light ray, aligned in the same direction as the first direction, or aligned in a direction slightly deflected from the first direction, while reflecting a linearly polarized light component aligned in a direction perpendicular thereto.
The direction of the polarization axis of the linearly polarized light component transmitted through the third polarizing splitter means may make an angle of 20xc2x0 or smaller with the first direction.
The direction of the polarization axis of the linearly polarized light component transmitted through the third polarizing splitter means may make an angle of 5xc2x0 or smaller with the first direction.
The second polarizing splitter means may reflect a linearly polarized light component aligned in a third direction perpendicular to the second direction.
The reflective means may be a total reflection optical element for reflecting the total of or most of the linearly polarized light component incident thereon.
The total reflection optical element may be a total reflection mirror for reflecting the total of or most of the linearly polarized light component incident thereon.
In one aspect of the present invention, the total reflection optical element may be third polarizing splitter means which reflects the total of or most of the linearly polarized light component aligned in the second direction while not reflecting the linearly polarized light component aligned perpendicular thereto.
The reflective means may be a partially reflective optical element for reflecting part of a linearly polarized light component incident thereon while transmitting the remaining incident linearly polarized light component.
The partially reflective optical element may be a half mirror, in which a metal thin film is formed on the surface of a light transmissive substrate.
The partially reflective optical element may be third polarizing splitter means which transmits a linearly polarized light component aligned in a fourth direction while reflecting a linearly polarized light component aligned in a fifth direction perpendicular to the fourth direction, and, because of a deflection between the fourth direction and the second direction, the third polarizing splitter means reflects part of a linearly polarized light component incident thereon, while transmitting part of the incident linearly polarized light component.
The display device may include a light source for backlighting, disposed diametrically opposite to the second polarizing splitter means with respect to the intervening reflective means, for emitting light toward the reflective means, wherein the display device displays predetermined information using a linearly polarized light component which is emitted from the backlighting light source, and transmitted through the reflective means, the second polarizing splitter means, the polarization axis varying means, and the first polarizing splitter means.
The display device may include first light diffusing means, disposed between the reflective means and the second polarizing splitter means, for transmitting an incident light ray while diffusing the incident light ray.
The display device may include second light diffusing means, disposed between the second polarizing splitter means and the polarization axis varying means, for transmitting an incident light ray while diffusing the incident light ray in a pattern different from a pattern imparted by the first light diffusing means.
The light diffusing means may diffuse the light ray through fine surface roughness.
The display device further include first coloration means, disposed between the reflective means and the second polarizing splitter means, for coloring an incident light ray to output a colored light ray.
The display device may further include second coloration means, disposed between the first polarizing splitter means and the second polarizing splitter means, for coloring an incident light ray to output a colored light ray.
The display device may further include first coloration means, disposed between the reflective means and the second polarizing splitter means, for coloring an incident light ray to output a colored light ray, and second coloration means, disposed between the first polarizing splitter means and the second polarizing splitter means, for coloring an incident light ray to output a colored light ray with a hue different from the hue imparted by the first coloration means.
The coloration means may be a color filter.
The coloration means may be a coloration layer attached on at least one of the plurality of polarizing splitter means.
The polarization axis varying means may include a liquid-crystal display element.
The display device may be incorporated in an electronic watch. The electronic watch incorporating the display device may display time and time measurement results in areas of the polarization axis varying means which are selected to be in a transmissive state that transmits the linearly polarized light component, transmitted through the first polarizing splitter means, therethrough with the polarization axis of the linearly polarized light component varied or in a transmissive state that transmits the linearly polarized light component therethrough with the polarization axis not varied.
The electronic watch may display time and time measurement results in a digital display in areas of the polarization axis varying means which are selected to be in a transmissive state that transmits the linearly polarized light component, transmitted through the first polarizing splitter means, therethrough with the polarization axis of the linearly polarized light component varied or in a transmissive state that transmits the linearly polarized light component therethrough with the polarization axis not varied.
The electronic watch may display time and time measurement results, in an analog display pattern corresponding to a watch hand, in areas of the polarization axis varying means which are selected to be in a transmissive state that transmits the linearly polarized light component, transmitted through the first polarizing splitter means, therethrough with the polarization axis of the linearly polarized light component varied or in a transmissive state that transmits the linearly polarized light component therethrough with the polarization axis not varied.
FIG. 1 is a diagrammatic view showing elements constituting a display device according to one aspect in connection with the display device of the present invention.
FIG. 2 is a diagrammatic view showing elements constituting a display device according to another aspect in connection with the display device of the present invention.
FIG. 3 is an explanatory view showing the operation of a transmissive type display using a light source for backlighting in the display device of FIG. 2.
FIG. 4 is a diagrammatic view showing a display device of FIG. 1 in which the invention according to another aspect is implemented.
FIG. 5 is a diagrammatic view showing a display device of FIG. 2 in which the invention according to another aspect is implemented.
FIG. 6 is a cross-sectional view showing one example of an electronic watch in which the display device of the present invention is incorporated.
FIG. 7 is a plan view of the electronic watch of FIG. 6.
FIG. 8 is a cross-sectional view of a movement of the electronic watch of FIG. 6.
FIG. 9 is an explanatory view of a polarizing splitter film for use as polarizing splitter means in the present invention.
FIG. 10 is a diagrammatic view showing the construction of the display device of a first embodiment of the present invention.
FIG. 11 is a diagrammatic view showing the construction of the display device of a second embodiment of the present invention.
FIG. 12 is a diagrammatic view showing the construction of the display device of a third embodiment of the present invention.
FIG. 13 is a diagrammatic view showing the construction of the display device of a fourth embodiment of the present invention.
FIG. 14 is a diagrammatic view showing the construction of the display device of a fifth embodiment of the present invention.
FIG. 15 is a diagrammatic view showing the construction of the display device of a sixth embodiment of the present invention.
FIG. 16 is a diagrammatic view showing the construction of the display device of a seventh embodiment of the present invention.
FIG. 17 is an explanatory view showing the operation of a transmissive type display using a light source for backlighting in the display device of FIG. 16.
FIG. 18 is a diagrammatic view showing the construction of the display device of an eighth embodiment of the present invention.
FIG. 19 is a diagrammatic view showing the construction of the display device of a ninth embodiment of the present invention.
FIG. 20 is an explanatory view showing the operation of a transmissive type display using a light source for backlighting in the display device of FIG. 19.
FIG. 21 is a diagrammatic view showing the construction of the display device of a tenth embodiment of the present invention.
FIG. 22 is a diagrammatic view showing the construction of the display device of an eleventh embodiment of the present invention.
FIG. 23 is a diagrammatic view showing the construction of the display device of a twelfth embodiment of the present invention.
FIG. 24 is a diagrammatic view showing the construction of the display device of a thirteenth embodiment of the present invention.
FIG. 25 is a diagrammatic view showing the construction of the display device of a fourteenth embodiment of the present invention.
FIG. 26 is a diagrammatic view showing the construction of the display device of a fifteenth embodiment of the present invention.
FIG. 27 is a diagrammatic view showing the construction of the display device of a sixteenth embodiment of the present invention.
FIG. 28 is an explanatory view showing the operation of a transmissive type display using a light source for backlighting in the display device of FIG. 27.